trap.js

var x = 3;
var y = 10;
var z = 100;
if (x != 3)
  y = 30;
  z = 50;

console.log(x); // 3
console.log(y); // 10 (not changed)
console.log(z); // 50 (changed!!!)

trap2.js

var x = 10;
var y = 10;
var z = 10;

var a = 0;
var b = 0;
var c = 0;
var d = 0;

if (x == 10)
  if (y != 10)
     a = 100;
     if (z != 10)
       b = 200;
  else
     c = 300;
     d = 400;

// Expected by intend:
// a == 0, b == 0, c == 300, d = 400

// Actual:
console.log(a); // 0
console.log(b); // b == 200
console.log(c); // c == 0
console.log(d); // c == 400